The present invention relates to a power-window apparatus for a vehicle, which apparatus can open and close a door window by a motor-driven mechanism.
A conventional power-window apparatus is operated by using an automatic reset type power-window switch in two steps. The first step (manual mode) operation of the switch in the direction of opening or closing the window energizes a window-opening relay or a window-closing relay through a contact by which a forward (positive) or inverse driving voltage is applied to a motor which rotates in a forward or reverse direction to move the window glass down or up to a desired extent. The second-step (temporary automatic mode) operation of the power-window switch in the window opening or closing direction actuates an auto-latching circuit for maintaining the window-opening or closing relay in an energized state to enable the motor to continue forward or reverse rotation until the window glass moves down or up to the full limit.
The conventional power-window apparatus for a vehicle, however, involves the following important problem.
The power-window apparatus having an auto-latching circuit normally works by energizing either the window-opening relay or the window-closing relay to apply a forward or inverse driving voltage to a driving motor of the power window mechanism depending upon the operation mode of the power window switch. However, in an accident of, e.g., the vehicle sinking into water, a control system of the auto-latching circuit may happen to energize both the relays, whereby the motor cannot rotate and the window cannot be open or shut by manipulating the power window switch.
The problem is serious because a person or persons cannot escape from the vehicle sinking into water if a driver cannot open any door window by the motor by manipulating the power-window switch.